Letters to the editor are presented in response to the article 'Large-Scale Complex IT Systems” by Ian Sommerville and colleagues in the July 2012 issue.
Letters to the editor are presented in response to the article 'Large-Scale Complex IT Systems” by Ian Sommerville and colleagues in the July 2012 issue.
We present a modular approach to implementing dynamic algorithm switching for parallel scientific software. By using a compositional framework based on function call interception techniques, our proposed method transp...
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We present a modular approach to implementing dynamic algorithm switching for parallel scientific software. By using a compositional framework based on function call interception techniques, our proposed method transparently integrates algorithm switching code with a given program without directly modifying the original code structure. Through fine-grained control of algorithmic behavior of an application at the level of functions, our approach supports design and implementation of application-specific switching scenarios in a modular way. Our approach encourages algorithm switching to dynamically perform at the loop end of a parallel simulation, where cooperating processes in concurrent execution typically synchronize and intermediate computation results are consistent. In this way, newly added switching operations do not cause race conditions that may produce unreliable computation results in parallel simulations. By applying our method to a real-world scientific application and adapting its algorithmic behavior to the properties of input problems, we demonstrate the applicability and effectiveness of our approach to constructing efficient parallel simulations.
Function call interception (FCI), or method call interception (MCI) in the object-oriented programming domain, is a technique of intercepting function calls at program runtime. Without directly modifying the original ...
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Function call interception (FCI), or method call interception (MCI) in the object-oriented programming domain, is a technique of intercepting function calls at program runtime. Without directly modifying the original code, FCI enables to undertake certain operations before and/or after the called function or even to replace the intercepted call. Thanks to this capability, FCI has been typically used to profile programs, where functions of interest are dynamically intercepted by instrumentation code so that the execution control is transferred to an external module that performs execution time measurement or logging operations. In addition, FCI allows for manipulating the runtime behavior of program components at the fine-grained function level, which can be useful in changing an application's original behavior at runtime to meet certain execution requirements such as maintaining performance characteristics for different input problem sets. Due to this capability, however, some FCI techniques can be used as a basis of many security exploits for vulnerable systems. In this paper, we survey a variety of FCI techniques and tools along with their applications to diverse areas in the computing and software domains. We describe static and dynamic FCI techniques at large and discuss the strengths and weaknesses of different implementations in this category. In addition, we also discuss aspect-oriented programming implementation techniques for intercepting method calls.
The ITERATOR pattern gives a clean interface for element-by-element access to a collection, independent of the collection's shape. Imperative iterations using the pattern have two simultaneous aspects: mapping and...
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The ITERATOR pattern gives a clean interface for element-by-element access to a collection, independent of the collection's shape. Imperative iterations using the pattern have two simultaneous aspects: mapping and accumulating. Various existing functional models of iteration capture one or other of these aspects, but not both simultaneously. We argue that C. McBride R. Paterson's applicative functors (Applicative programming with effects, J. Funct. and Program., 18 (1): 1-13, 2008), and ill particular the corresponding traverse operator, do exactly this, and therefore capture the essence of the ITERATOR pattern. Moreover, they do so in a way that nicely Supports modular programming. We present some axioms for traversal, discuss modularity concerns and illustrate with a simple example, the wordcount problem.
A logic circuit of the adaptable unit intended for controlling the processes of measurements and experimental data acquisition is presented. The adaptation to the particular measurement type is attained by combining a...
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A logic circuit of the adaptable unit intended for controlling the processes of measurements and experimental data acquisition is presented. The adaptation to the particular measurement type is attained by combining all base components of the unit and its software in separate interchangeable program and electronic assemblies. The prototype of the unit is designed as an example of the automatic setup intended for measuring spectral dependences of physical quantities. A possibility of the adaptation is shown using the example of modifying the implemented circuit for measuring volt-ampere characteristics.
A modular simulation program of absorption heat pumps, refrigerators and air conditioners is developed under Mathematica (A (R)). The modular approach is an easier way to simulate various complex configurations. A com...
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A modular simulation program of absorption heat pumps, refrigerators and air conditioners is developed under Mathematica (A (R)). The modular approach is an easier way to simulate various complex configurations. A comparative study between the simulator's results-temperatures, pressures, refrigerant concentrations, heat duties, flow rates, overall heat transfer parameters and coefficient of performance (COP)-and experimental measurements shows a favorable agreement. The usefulness of the present program in performance analysis of thermodynamic cycles is thus established.
Discusses the development of a software-flexible, hardware-economic, modular machine vision system for education. Purpose of developing a machine vision system for education; Description of hardware components and sof...
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Discusses the development of a software-flexible, hardware-economic, modular machine vision system for education. Purpose of developing a machine vision system for education; Description of hardware components and software architecture; Examples of how the system can be used; Limitations of the system.
This paper describes how line drawings and continuous tone shaded images of a three-dimensional solid model of a brain structure are generated using a powerful general purpose computer graphics package. The model is b...
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This paper describes how line drawings and continuous tone shaded images of a three-dimensional solid model of a brain structure are generated using a powerful general purpose computer graphics package. The model is built from a series of serial sections. We developed a software interface to convert the data entered by a section oriented way into a brain structure oriented file. We point out particularly the modular approach which consists of separating the tasks on small microcomputers or on bigger machines according to their computing cost. An example of a thalamic structure in a stereotaxic referential is presented.
Application development today is too labor-intensive. In recent years, very high-level languages have been increasingly explored as a solution to this problem. The Business Definition Language (BDL) is such a language...
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Application development today is too labor-intensive. In recent years, very high-level languages have been increasingly explored as a solution to this problem. The Business Definition Language (BDL) is such a language, one aimed at business data processing problems. The concepts in BDL mimic those which have evolved through the years in businesses using manual methods. This results in three different sublanguages or components: one for defining the business forms, one for describing the business organization, and one for writing calculations.
Historically, information technology departments have cycled between centralized and decentralized application software distribution, although modular program design and enterprise management software may break that c...
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Historically, information technology departments have cycled between centralized and decentralized application software distribution, although modular program design and enterprise management software may break that cycle. Meanwhile, IT departments that want to manage the distribution and configuration of software across their networks are searching for an acceptable balance of control, reliability, and speed. Distributing application files on individual PCs maximizes network performance, but makes it much more difficult to enforce configuration standards and maintain control. Placing application files in a few central locations gives an IT department significant control over software configuration but may degrade network performance and lead to user dissatisfaction.
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